Japanese Unexamined Patent Publication No. 2002-160581, which is assigned to the applicant of the present invention, discloses an AFS for improving a driving safety of a motor vehicle. The AFS is shown schematically in FIG. 1. A motor vehicle (CAR) includes a steering sensor 1A for detecting a steering angle in the steering apparatus and a vehicle speed sensor 1B for detecting a vehicle speed. Output signals from the sensors 1A and 1B are provided as input signals to an electronic control unit (“ECU”) 2. Headlamps 3 (e.g., swivel lamps 3R and 3L) are disposed in the right and left sides of a front portion of the motor vehicle. The ECU 2 deflection controls a range of radiation of the headlamps 3, for example, by controlling the horizontal direction based on the received input signals so as to change the light distribution characteristics.
According to the AFS, when the motor vehicle travels on a curved road, it is possible to illuminate a front of the curve by controlling the radiation direction of the swivel lamps in accordance with the steering angle of the motor vehicle, and it is effective for improving the driving safety.
In the AFS mentioned above, when the deflection control operates the right and left swivel lamps based only on the steering angle, certain problems may arise. Conventional attempts to address those problems have included the following. For example, when the motor vehicle turns to the left in a narrow intersection, a steering operation is performed to move the motor vehicle forward at an acute angle with respect to the road ahead of the vehicle after making the turn by temporarily turning the steering wheel to the right to move the motor vehicle outward toward the right and, thereafter, turning the steering wheel leftward. When deflecting the swivel lamp in accordance with the steering angle, the swivel lamp is deflected toward the right by the first rightward steering. Accordingly, after the left turn, the road ahead of the vehicle cannot be illuminated until the steering wheel is turned leftward, resulting in an unsafe driving condition.
Further, just after turning to the right or the left, the steering wheel remains turned to the right or the left. Accordingly, if the swivel lamp remains deflected to the right or the left until the steering wheel is returned, it is impossible to properly illuminate the front of the vehicle in the straight traveling direction ahead of the curve just after the right turn or the left turn. In some cases, an unsafe driving condition may occur.
When changing lanes while the motor vehicle is traveling on an express highway, the steering operation is executed by issuing a turn signal and subsequently turning in the direction thereof. If the swivel lamp is deflected only in accordance with the steering operation, illuminating the front of the vehicle in the straight traveling direction may be insufficient, for example, when a steering operation is performed to turn the vehicle in the direction opposite the turn signal, such as in an emergency or in order to avoid a danger. In such situations, there is a risk that an unsafe driving condition may result.
The present invention may provide a vehicular lightening apparatus which can achieve suitable lighting by limiting deflection of the lamp, while the vehicle is traveling, when it is not desirable to deflect in accordance with a steering operation.